The long range objective of our laboratory continues to be the elucidation of the mechanisms by which amino acids and various other substances are transported into the lens and across the blood-aqueous and blood-vitreous barriers and the possible aberrations in these mechanisms which may contribute to the pathogenesis of cataract and other ocular abnormalities. Specific areas of investigation, many of which are currently in progress, are: the metabolism and function of glutathione in the lens, the high level of myoinositol and its relation to amino acid transport, the role of cations in the transport of amino acids into the lens and other ocular structures. Other aspects of the proposed program will include the study of the steady state composition of amino acids in plasma and intraocular fluids and lens, transport of amino acids across the blood-aqueous and blood-vitreous barriers, the metabolism of amino acids in the lens, studies on protein-bound glutathione in normal and cataractous lenses and the role of glutatione as a carrier for amino acid transport in the lens. There is an intimate relationship tying together all of these specific areas of investigation, insofar as the supply of amino acids to the lens not only depends on the transport mechanisms across its surface membranes, but on the availability of these compounds in intraocular fluids. While many of these areas will be studied in the normal lens, we will also have an opportunity to look into these and other parameters in cataractous lenses and other ocular structures in diabetic and galactose-fed animals.